LaVar Burton directed an episode of Star Trek: The Next Generation, on which astronaut Mae Jemison
played the transporter operator (images bottom, right). In the commentary following the 6th season on DVD (interview November 8, 2001, on disc 7, "Communications: Bold New Directions"), he said:

Mae Jemison was really thrilling for me because May and Whoopi and I are all fans of the show and have had the conversation among ourselves that Star Trek was hugely important to us as kids when we were growing up.

I read a lot of science fiction books, as a child. Science fiction was pretty much my body of literature of choice and it was rare, it was not very often, that I encountered heroes in the pages of those novels who looked like me.

So in Mae’s case, Mae Carol Jemison, first African-American woman in space, flew a shuttle mission— became first a scientist and then an astronaut because she watched Star Trek, and one of the messages that she received was that “This is a job that’s possible for you, too, little girl.” And so, to be able to bring Mae on Star Trek in an episode that I directed and just have her be transporter chief, but even more than that, to have Nichelle come by that day and to have the two meet was huge… huge.

For those who aren't Star Trek Fans, Whoopi is Whoopi Goldberg, who played the wise Guinan in TNG (The Next Generation), and Nichelle is Nichelle Nichols, who played Uhura, the communications officer, in the original series, pictured just below.